Short-chain fatty acids such as acetic acid, propionic acid and butyric acid are produced by the fermentation of indigestible carbohydrates derived mainly from food by intestinal bacteria in the lower gastrointestinal tract. The short-chain fatty acids are not only utilized as a primary energy source for large intestine mucous membrane epithelial cells but exhibit many physiological effects. Particularly, butyric acid is considered to exhibit diverse physiological activities such as an epithelial cell growth-promoting effect, an anti-inflammatory effect and a bowel motility-enhancing effect (Non Patent Literatures 1 and 2). Also, it has been suggested that butyric acid is important for the prevention of colorectal cancer or ulcerative colitis (Patent Literature 1). In recent years, butyric acid has been reported to promote the secretion of gastrointestinal hormones from the lower gastrointestinal tract (Non Patent Literature 3) and to increase energy consumption in peripheral tissues through oral administration to suppress obesity while improving insulin resistance (Non Patent Literature 4), for example.
Certain bacteria of the genus Lactobacillus and the genus Bifidobacterium are known as agents for promoting a rise in intestinal butyrate concentration (Patent Literature 1). Also, bacteria belonging to Anaerostipes, particularly, Anaerostipes hadrus (Eubacterium hadrum) (hereinafter, referred to as A. hadrus) DSM 3319T, Butyrate-producing bacterium SSC/2, Butyrate-producing bacterium SS2/1 and the like are known as bacteria producing butyrate (Non Patent Literatures 5, 6 and 7).